This invention generally relates to an apparatus for reducing backlash in a rod motion controller, and more particularly to an apparatus that uses a backlash reducer to substantially reduce or eliminate backlash in the rod motion controller.
Many structural and mechanical applications require the use of moving rods and linkages that need to be secured in different modes, including fail-safe modes. For example, overhead doors on airframes that are actuated by rods driven by pneumatic pressure should be fitted with a device that will prevent accidental closure of the door in case of pneumatic pressure failure. Other applications require that rod or linkage position be maintained after positioning. One good solution to these problems is a rod retaining mechanism such as a rod motion controller.
Rod retaining mechanisms restrain relative motion between the rod and the rod retaining mechanism. By connecting the rod retaining mechanism to a mount, the rod may be retained and its motion thereby arrested with respect to the mount. Rod retaining mechanisms are typically manufactured with specified manufacturing tolerances. Because typically more than one part cooperates in a rod retaining mechanism to achieve the desired results, the net effect is to magnify any operational deficiencies due to specified manufacturing tolerances. One type of operational deficiency caused by specified manufacturing tolerances in prior art rod retaining mechanisms is backlash. Backlash is the undesirable movement of the rod after engagement of the rod retaining mechanism. Backlash is due to the internal design of the rod retaining mechanism and arises from the internal movement of restraining devices as they actuate to grab the rod and as they actuate to stop or lock the rod. While using high tolerance parts in the rod retaining mechanism could potentially reduce backlash, high tolerance parts are expensive, impractical, or may be impossible to produce due to material and manufacturing limitations and may not always result in an acceptable level of backlash reduction. When the force on the rod changes magnitude or direction, any backlash in the rod retaining mechanism will result in motion of the rod in an undesirable direction.
Therefore, it is the motivation of the invention to provide a novel motion control apparatus for use with a rod with reliable reduction in backlash.